Pheromones are defined as substances that are used for communication between individuals of the same species. Pheromones are usually obtained in the form of mixtures through multiple separation steps including organic solvent extraction and liquid column chromatography.
In early 1980s, it was reported that C. elegans can secret a type of pheromone, termed ‘dauer pheromone’, a constitutively secreted substance serving as an indicator of population density (Golden and Riddle 1982, Golden and Riddle 1984a, Golden and Riddle 1984c), which can induce C. elegans into dauer arrest phase when they are faced with adverse environmental conditions such as heat, lack of food, and crowdedness. Although its presence has been known for more than two decades, its structure, molecular weight and physical properties are not known yet (Riddle, D. L., Science, 218: 578–580, 1982).
According to the previous studies, pheromone secreted from C. elegans exists in extremely low concentration. Because of its potential in control of aging and stress in C. elegans, the dauer pheromone has been studied extensively. However, until now, because it was not available in a single molecule, most investigators have used the crude extracts of C. elegans that are believed to contain a dauer pheromone and other compounds as well.
Therefore, it is necessary to isolate a pure dauer pheromone from the extracts and characterize its structure for the studies of aging, stress and other cellular function of C. elegans. The dauer pheromone is likely to be detected by as yet unidentified pheromone receptor that couples to a cyclic GMP signaling pathway that includes daf-11 (Birnby et al. 2000). It has been known that the dauer pheromone of C. elegans is very stable and hydrophobic, and has chromatographic properties similar to those of hydroxylated fatty acids and bile acids.
In this article, we describe purification, identification, and molecular characterization of C. elegans-specific dauer pheromone.